Method of wireless signaling



,April 12, 1927. 1,624,005

M. OSNOS ET AL Tl-10D 0F WIRELESS SIGNALING Filed Jan. 12; 1923 Patented Apr. 12, 1927.

sures PATENT OFFICE.

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Application filed January 12, 1923, Serial No. 612,283, and in Germany January 12, 1922 It has been generally assumed that a saturated iron core choke 0011 without supermposed direct current 1s capable of gencrating only odd multiple harmonics (see for instance, Joly, German Patent No. 264,250, page 2, lines 85-90).

However, we have succeeded in producing even, as well as odd, harmonics of the basic wave of the machine feeding installation. Such result has been obtained in the well known frequency multiplier in a stage by means of saturated iron core choke coils and without superimposed direct current. The waves obtained were powerful and had a good operating radius.

In the drawing- Fig. 1 is a diagrammatic representation of a circuit arrangement which may be employed in the practice of the invention;'

Fig. 2 is a diagrammatic representation of a circuit arrangement of modified form;

Figs. 3 and 3 are detail views of the alternating current windings of the iron core choke coil and show the windings in series and in parallel respectively.

Fig. 4 is an end View of the preferred arrangement of the direct current windings for the iron core choke coil, and

Fig. 5 is a diagrammatic representation of an arrangement of the alternating current windings of the iron core choke coil which may be used when it is desired to avoid the necessity of utilizing a direct current winding.

Let us consider, for instance, the frequency multiplying circuit shown in Fig. 1 of the accompanying drawings. In this figure 06 is the machine feeding the installation, L and C with their corresponding reference numerals indicate inductances and capacities. (Z is the saturated iron core choke coil, L K is the coupling coil, and A is the antenna.

It has been generally assumed that such a circuit will produce only odd multiples of the frequency of the generator a. We have discovered, however, that by suitably proportioning' the tuning means L and C and the ohmic resistances and by suitably adjusting the coupling of the individual circuits, favorable conditions may be obtained for the excitation of even rather than odd harmonics of the basic frequency. The harmonics of even multiples which are then most favored by the excitation can be made to substantially, suppress the other harmonics includmg the odd harmonics. The proper adjustment of the tuning means is best obtained by experimenting andcontinuously varying these means,- e. g, by adjusting the self induction of the individual circuits.

The occurrence of the desired effect may be explained as follows.

As far as its magnetic condition is concerned, the station is neither during itsoperation nor during its starting quite mathematically symmetrical with respect to the positive and negative halves of the wave of the potential or the current. This is true eyen ifthe dissymm'etries are unnoticeably slight. Due to this, the source of energy, that is, the generator or the like, may obtain traces of the dissymmetry. Strictly speaking the choke coil will similarly always contain the traces of magnetism due, for example, to the preceding magnetic condition. At any rate this magnetism may always be produced by means of a current impulse, which will be discussed later in describing the method of starting. The iron core choke coil will therefore behave as though this slight premagnetizing were preduced by means of a small superimposed current. The field of the choke coil will always be assymmetric even if only to a slight degree, e. g. the positive swing of the field wave is never quite congruent with the negative swing, and, analytically speaking, this means that at least embryonic even harmonics are present. In a similar manner traces of the harmonics of the other than even multiple frequencies may be present if, for instance, a plurality of successive demagnetiz'ing cycles are different and only whole groups of cycles are equal. In that case the duration of each of said groups of cycles may be considered as the period, and the higher miiltiple harmonics of this period appear as liar monies of fractional frequency with respect to the basic wave of the source. These harmonies appear therefore as the harmonics of a basic wave which is longer than the basic wave ofthe generator and which is either non-existent in the whole station or only the traces of which may exist. The above mentioned harmonics of fractional frequency and their longer basic waves may suitably be designated as quasi-harmonics.

The even harmonics and the quasi-harmonics which are always present in embryonic form are under usual conditions too small and unstable to generate lasting energy oscillations that may be measured. In accordance with the present invention these harmonics are strengthened by conducting them into correspondingly timed paths. For instance, the wave of four-fold frequency is developed it the capacity and inductance of its circuit are so tuned that the resulting impedance of the circuit has an essentially capacitive character for the corresponding frequency so that the current of this frequency will advance with respect to its E. M. F. In this manner, its field and. therefore, the E. M. F. are strengthened whereby the current will in this manner swing itself to a high value and will suppress the other waves. In a similar manner we may produce waves of other frequencies (e. g. 6 fold, 8 fold, etc.). e have also succeeded in producing the 13 fold, 17 fold, 19 fold harmonics of the basic wave of kilometers whereas the basic wave of the generator was only 30 kilometers.

It will be seen therefore that in accordance with the present invention, unlike the customary generation of harmonics in accordance with which the waves were forced from the beginning by the terminal potential supplied from the outside and the field distribut-ion determined thereby, harmonics of even and fractional frequency may be produced.

For the purpose of obtaining the desired wave, the antenna shown in the diagram of Fig. 1 is tuned to the desired frequency by means of the extension coil L, and at the same time the coupling and tuning means L 0 are so adjusted that the measuring instruments will indicate the maximum out put when the antenna wave is pure. If necessary, the system L G may also be subsequently tuned.

The embodiment shown in Fig. 2 differs from the above in this that instead of an inductive coupling, the output circuit is directly coupled with the iron core choke coil (Z. The two circuits III and IV may be connected to the same terminals of the choke coil (Z as in Fig. l or, as indicated by the adjustable taps, the connection may be made to different terminals.

If the antenna itself has a suitable capacity for producing the desired harmonic, the condenser C may be left out of the circuit shown in Fig. 2, and the tuning to the desired wave may be effected mainly by means of the variometer L Any well known detuning method. may be used in key sending or telephony. Thus the whole main circuit may be broken, or a portion of the main circuit or an inductance or capacity provided in another circuit may be short-circuited and again switched in, or a well known detuning choke coil which may be adj ustcd by means of direct current. Furthermore, the experiments have shown that detuning may be obtained also by varying the ohmic resistance and this may be switched in and out by closing and opening a short-circuiting key t (Fig. 2).

Finally, the desired detuning may be accomplished by additional direct current energization of the iron core choke coil (Z, whereby the corresponding waves are produced by switching in the direct current.

Direct current energization may also be used for starting the station. For this purpose it is sutlicient momentarily to close and open the direct current circuit. The brief direct current impulse thus obtained will cause the station to operate after the disappearance of the direct current. In order in this case to avoid the inducing of large potentials in the direct current winding it is advisable to divide the alternating current winding of the choke coils into two halves Z and Z on two equal iron cores, said halves being differentially wound with respect to the direct current winding. Figs. 3 and 3* show such a circuit arrangement in which the alternating current windings Z and Z of the choke coil are arranged in series and parallel respectively. In the use of a circuit such as is shown in Fig. 3 it is advisable to connect a condenser G in parallel with the direct current winding 9 and battery 6 in order to absorb the balancing currents which are produced after the closing and also immediately upon the opening of the key S. Instead of the condenser C a special short circuiting winding may be used. This winding would be closed and of the same direction as the direct current winding.

In the use of the parallel circuit arrangement shown in Fig. 3, the balancing condenser C may be omitted because both windings Z and Z constitute short circuits for the mentioned balancing currents.

The preferred physical arrangement of the direct current windings is shown in Fig. 4 in which (Z and (Z, are the two iron cores of the coil. For the sake of clearness the alternating current winding is not shown in this figure and may be arranged either in the manner shown in Fig. 3 or in the manner shown in Fig. 3*.

If it is desired to avoid the necessity of providing a separate direct current winding, then the rhomboid circuit well known in frequency multipliers may be used. Such a circuit arrangment is shown in Fig. 5. In this figure the windings Z and Z, are pro vided on one iron core and the windings Z and Z on the other iron core. h and 10 are the alternating current terminals and Z and Z, are the direct current terminals.

It should be noted also that the key and starting method described in connect-ions with Figs. 3 and 5 may be used not only for loo LEO

generating even and quasi-harmonic overwaves but also for generating odd harmonic over-waves.

The current may be cut in either by tapping and letting go of the key 8 after the switching in of the generator or vice versa by first tapping and letting go of the key 8 and then switching in the generator.

The key or starting winding 9' may be supplied with a low frequency current iustead of direct current.

Having described our invention, what We claim is:

1. A method of producing even harmonics of a basic frequency without the superimposition of direct current by means of a circuit arrangement comprising a saturated iron core choke coil, and a tuned path, which consists in conducting the desired harmonic into the correspondingly tuned path, the capacity and inductance of the tuned path being so proportioned that the resulting impedance of the path has an essentially capacitive character for the frequency of the desired harmonic so that current of such frequency will advance with respect to its electromotive force, thereby causing the current to be strengthened and to suppress waves of other frequencies.

2. The method of starting a system for producing harmonics without the superimposition of direct current, said system comprising a generator of a fundamental frequency, and a saturated choke coil, which comprises, cutting in the said generator and momentarily subjecting said choke coil to direct current magnetization.

3. The method of starting a system for producing multiple frequencies from a fundamental frequency, said system comprising a generator of the fundamental frequency and a saturated'choke coil, which comprises, cutting in the said generator and subjecting said choke coil to direct current magnetization, then cutting out the magnetizing current thereby permitting the current produced in the choke coil by the combination of the frequencies to maintain the same electrical conditions.

MENDEL OSNOS. LEO KASARNOW SKY. 

